Preparation of printing-plates.



M. ULLMANN.

PREPARATION OF PRINTING PLATES. APPLIOATION FILED 00122, 1908.

1 34 75 Patented Aug. 6, 1912.

WITNESSES.

INENTOI? Arm/Mrs. I

MAX ULLMANN, OF ZWICKAU, GERMANY.

PREPARATION OF PRINTING-PLATES.

Specification of Letters Patent.

Patented Aug. e, 1912.

Application filed October 2, 1908. Serial No. 455,924.

To all whom it may concern:

Be it known that I, MAX ULLMANN, a citizen of the Empire of Germany,residing in Zwickau, in the Kingdom of 'Saxony, in said Empire, haveinvented certain new and useful Improvements in the Preparation ofPrinting-Plates, of which the following is a specification.

This invention relates to an improvement in the process of treatingprinting plates by direct exposure in the photographic camera anddescribed in the application Serial No.

400,693 by the same inventor, and has for its object to provide aspecial treatment of the plates after exposure and develo ment, in orderto procure specially sharp plctures.

The first part of the process consists in preparing a printing platebyrendering its operative surface sensitive to light by coating thesurface with a sensitive solution film, exposing the sensitive filmwhereby the exposed parts are rendered resistive to acid, thendeveloping the plate whereby the unexposed parts are removed and thusdepressed, and the exposed parts remain in relief. The plate is thendried'and the depressed portions filled with fat color or ink. This muchof the process is the same as that which forms the subject of theinvention of my application hereinbefore mentioned. After this much ofthe process has been performed a test print, or-proof, may be made andif the fine lines do not show quite sharp and distinct the process iscontinued, and this continuation of the process constitutes the presentinvention. The ink is placed in the depressions as in the formerapplication and the plate resubmitted to the development. The plate isthen dried and the depressions filled, with ink as before and the platemay be printed from. It will be found that the roughness has beenremoved from the fine lines.

film, a part of which has been exposed to light, Figs. 2 and 3 showsectional perspective views ofthe film taken on the line XX of Fig. 1during the various steps of the process. Fig. 2 shows the plate afterbeing developed and rolled in ink, and Fig. 3 shows the plate ready forprinting.

The base 1 of the plate carries thereon the sensitive film 2 which isrepresented as having been exposed to'light, the design to be reproducedbeing the unexposed parts 3 of the ,film.

The film 2 may be composed of a coating of liquefied gelatin andchromate of ammonium with the addition of ammonia and is renderedresistive to acid by exposure to light.

After exposure the film is developed, which may be done by immersing theplate in a bath of dilute nitric acid, which causes the removal of theunexposed parts 3 of the film, these partsbeing the lines and points ofthe drawing, thus forming the depression 4.

The plate is then dried. The plate is then rolled in fat color or ink,and the ink is then wiped from the face of the film. After this, theplate is again immersed in the developing bath, thus completing theplate, after which the plate may be rolled in ink, as shown in Fig. 2,and then wiped ofi, leaving the plate ready for printing, as shown inFig. 3.

Having thus described my invention, I claim as new and desire to secureby Letters Patent:

The herein described process of preparing a printing plate, consistingin rendering the operative surface of the plate sensitiveto light bycoating it with a film comprising liquefied gelatin and chromate ofammonium with addition of ammonia, exposing the plate whereby theexposed parts of the film are rendered resistive to acid, developing theplate in a bath of dilute nitric acid whereby the unexposed parts of thefilm are removed thus forming depressions in the film at said parts,drying the plate, rolling the film with ink, again developing the platein a bath of dilute nitric acid, and drying the plate for use.

The foregoing specification signed at Berlin, Germany, this sixteenthday of September, 1908.

I MAX ULLMANN.

